to lower *K*Ic) and the mesh is better able to capture

there is a nearby pre-existing crack. For the Locks

27 monolith, data on the exact condition of the

them.

interface bond and foundation does not exist. If it

is assumed that the interface bond is perfect and the

(4) Normal stress profiles.

monolith and foundation materials are homogeneous

and defect free, the crack may curve away from the

(a) The normal stress (effective stress) profiles

interface, as the crack length increases beyond

along the base of the monolith for crack lengths of

9.0 ft.

6.0 to 13.02 ft are shown in Figure A-10. The

normal stress profiles are virtually identical for

(3) Crack opening displacement profiles. The

distances along the base of the monolith up to

crack opening displacement (COD) profiles for

25.0 ft. Beyond 25.0 ft, the normal stress profiles

assumed crack lengths of 6.0 to 13.02 ft are shown

diverge. This lack of sensitivity to the crack length

in Figure A-9. The COD profiles for crack lengths

in the normal stresses at less than 25.0 ft is the

of 6.0 through 10.5 ft exhibit noticeable kinks near

result of the relatively large culvert in close proxim-

the crack tip which are not evident for longer crack

ity to the interface between the monolith and the

lengths. This effect is a function of the coarseness

foundation. There is only 8.0 ft between the bottom

of the mesh. As described, these results represent

of the culvert and the top of the foundation and the

cases where *K*Ic = *K*I of Table A-2. For shorter

width of the culvert is almost one third that of the

entire monolith. The portion of the monolith under

crack lengths KIc would be larger; therefore, higher

the culvert lacks sufficient stiffness to transfer verti-

tensile stresses can develop at the uncracked region

cal stresses, effectively isolating the right side of

near the crack tip causing higher displacement

the monolith from the left side near the base. In

gradients. The mesh is too coarse to capture the

order to further determine the effect of the culvert,

high displacement gradients evident for shorter

an additional series of analyses was performed in

crack lengths; therefore, some distortion of the

which the culvert was not considered. The results

plotted displacements occurs in the region near the

of these analyses are summarized in Appendix B.

crack tip. As the crack length increases, the dis-

placement gradients near the crack tip decrease (due

A-11